Brake systems for automatically shutting down the engine and/or stopping the rotating blade of a lawnmower or other powered implement when the operator is not using the lawn mower or other powered implement are known in the art. These brake systems have come to be known as “deadman” brake systems.
Existing deadman brake systems typically consist of two parts, a positive braking mechanism disposed within the engine, and a lever disposed at the upper handle portion of the lawn mower. The lever is connected by a cable to the braking mechanism for actuating the braking mechanism. The braking mechanism is normally biased into a position such that the braking mechanism engages the flywheel, thereby preventing or stopping rotation of the crankshaft. Opposite biasing, and thus disengagement of the braking mechanism from the flywheel, is accomplished when the operator actuates and holds the lever against the upper handle portion. In order to keep the engine running, the lever must remain biased by the operator. Once the lever is released, the natural bias of the system moves the braking mechanism back into engagement with the flywheel, thereby stopping the engine.
It is also known in the prior art to include an ignition kill switch with the deadman brake system. In existing arrangements, when the brake mechanism is in its braking position, the kill switch connects the ignition circuit to ground, grounding or shorting out the primary coil of the ignition transformer so that no current will flow into the primary coil, thereby bypassing and preventing the spark plug from firing.
In existing systems, the grounding of the ignition circuit is accomplished by contacting the kill switch (or kill scraper) with the mechanical brake arm that engages the brake pad. This arrangement suffers from a number of deficiencies, including: (1) the use of many components and complex bends to perform the required function; and (2) increased space requirements as the mechanical brake arm in these systems require a greater degree of travel because the arm must accomplish both tasks of operating the brake and contacting and engaging the switch. Furthermore, by nature of the location of the kill switch near the cutting blade of the lawn mower, there is an increased possibility that the terminals of the kill switch can be become covered with debris that could prevent and/or delay the grounding of the ignition circuit. Thus, a need exists for an improved and simplified deadman brake system and engine powered implement incorporating the same.